As one of crystal resonator plates, a tuning-fork type crystal resonator plate is known, which is made up of a base portion and two leg portions protruding from the base portion (see, for example, Patent Document 1). Such a tuning-fork type crystal resonator plate includes: a pair of excitation electrodes having different potentials formed on the two leg portions; and concave grooves formed in both main surfaces of the two leg portions. A turning-fork type crystal resonator device is made by hermetically sealing the tuning-fork type crystal resonator plate within an inner space of a main body casing made up of a base and a lid (see, for example, Patent Document 1).